Field of the Invention
The present invention relates to a method for producing a toner that is used in, for example, electrophotographic methods, electrostatic recording methods, and magnetic recording methods.
Description of the Related Art
Image-forming apparatuses, e.g., copiers, printers, and so forth, have in recent years been subjected to increasing diversification with regard to their intended applications and their use environment, and along with this ever greater energy savings are being required. Toner that presents additional improvements in the low-temperature fixability is the first consideration from the standpoint of toner-based improvements in energy savings.
Crystalline substances, e.g., waxes, are used in order to improve the low-temperature fixability of toners. The crystalline substance melts at the melting point exhibited by such a material and plasticizes the binder resin used in the toner and thereby promotes melting and deformation of the toner. As a consequence, the low-temperature fixability of a toner can be further enhanced by lowering the melting point of the crystalline substance and/or increasing the amount of use of the crystalline substance.
On the other hand, the storability of a toner in a high-temperature, high-humidity environment is increasingly impaired as the low-temperature fixability is enhanced. Since the crystalline substance plasticizes the binder resin in the toner, when the toner is left to stand in a high-temperature environment, for example, at 50° C., the crystalline substance outmigrates to the toner surface and the toner then coalesces with another toner and this produces the storability-related problem of toner blocking.
As a result, a trade-off relationship between the low-temperature fixability and the storability is set up when enhancements are sought in the low-temperature fixability through the use of a crystalline substance.
The low-temperature fixability can be enhanced by controlling the state in which the crystalline substance is present in the toner interior. For example, the low-temperature fixability is enhanced for a state in which the crystalline substance is dispersed in the toner interior, in comparison to that for a state in which it is present aggregated without dispersion.
In Japanese Patent Application Laid-open No. 2009-104193, inter alia, the low-temperature fixability is enhanced by causing the crystalline substance to be dispersed in the toner interior through an increase in the cooling rate.
On the other hand, in relation to the storability, a method in which the degree of crystallinity of the crystalline substance in the toner interior is increased is described in Japanese Patent Application Laid-open No. 2015-28616.
However, there is still room for additional improvements in order to overcome the trade off described above, i.e., avoiding a loss of storability while enhancing the low-temperature fixability.